Re: [PATCH] pretty-print: de-tabify indented logs to make things line up properly

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mar 16, 2016, 18:21 UTC
Message-ID: <CA+55aFxV5PWdSn9Gj=zV464TtJo=QvciZrhc5Pwe+Qfyqt8sXw@mail.gmail.com>
In-Reply-To: <xmqq7fh25mkc.fsf@gitster.mtv.corp.google.com>

On Wed, Mar 16, 2016 at 11:01 AM, Junio C Hamano <gitster@pobox.com> wrote:

>
>  (1) if turning your "preparation; do { ... } while()" into
>      "while () { }" would make the result a bit easier to read;

So it's probably partly taste, but I will also disagree with your "easier to read", because of the way the code is logically structured.

In particular, the "no TAB" case is actually *fundamentally* different from the "no TAB at the end" case. The return value is different, and the caller does very different things - the code tries to make it very clear that that "no TAB" situation is very different from "we found a TAB".

So it's not "preparation + do-while".

It's "preparation + handle the no-TAB case differently", and then the "do-while" is very natural because by the time we get to the "ok, we are now going to need to do something about the line" stage, we already know we have a tab.

But the code *could* be made to just always do the whole "strbuf_add()", and not return a return value at all, and the no-tab case wouldn't be explicitly written to be different.

Let me know if you'd prefer that variant, and I'll send a new version.

>  (2) if we can somehow eliminate duplication of "tab + 1" (spelled
>      differently on the previous line as "1+tab"), the end result
>      may get easier to follow.

Yeah, I considered that. Either by just doing "tab++" before (so the +1" would come from that in both cases), or by introducing a new variable like

    ptrdiff_t bytes_used;
    ...
    bytes_used = 1 + tab - line;

and then just doing

    line += bytes_used;
    linelen -= bytes_used;

and the code I wrote just didn't do any of those temporary updates, and instead just did the "+1" by hand in both cases.

Again, I can redo the patch, just tell me which model you prefer.

                 Linus